1. Field of Invention
The present invention relates to an electrical junction box for a vehicle, in particular a box to be connected to a wire harness for a vehicle. The invention is intended to provide a junction box which is thin and compact even though the number of circuits is increased. The invention also provides a vehicle, such as an automobile, having the electrical junction box mounted on it.
2. Description of Related Art
Recently, the rapid increase in the number of electric and electronic component parts which are mounted on a vehicle has led to increase in the number of circuits to be accommodated in a junction box in the vehicle. When forming branch circuits at high density, it is necessary to mount a large number of component parts on the junction box, which increases the number of assembly stages.
The assignees of the present application proposed the junction box 1 shown in present FIG. 21 in JP-A-2000-112691 (corresponding to EP-A-1145914 and U.S. patent application Ser. No. 09/833,595). The junction box of FIG. 21 is intended to be thin, capable of permitting circuit alteration and reducing the time and labor required for its assembly from component parts.
In the junction box 1 of FIG. 21, a connector connection circuit (base circuit), a fuse connection circuit, and a relay connection circuit provided in the junction box are formed separately as a connector module 2, a fuse module 3 and a relay module 4. The connector module 2, the fuse module 3 and the relay module 4 are incorporated in the casing composed of the lower case part 5 and the upper case part 6.
In each of the connector module 2, the fuse module 3 and the relay module 4, bus bars 2b, 3b and 4b are fixed to insulation substrates 2a, 3a and 4a respectively, and project from the periphery of the insulation substrates to which they are attached.
Because the whole circuit of the junction box is divided into the connector module 2, the fuse module 3 and the relay module 4, overlap of the bus bar tabs can be avoided. Thus, the formation of multiple layers of bus bars can be prevented. Therefore, the junction box can be thin, and the circuits of the bus bars can be more easily wired. Thus, it is possible to reduce the area of the bus bar for each module. Consequently, even though the connector connection bus bars, the fuse connection bus bars and the relay connection bus bars are formed separately, the total area of all the bus bars can be reduced and the area of the junction box can be kept to a minimum.
Further, when the specification of any one of the connector circuit, the fuse circuit and the relay circuit is altered, it is only necessary to alter the respective module. Thus, the junction box permits alteration of the specification easily.
However, the bus bars used as electrical conductors in the modules are generally formed by punching metal sheet into a form corresponding to a complicated configuration of the circuit of the module. Thus, the yield of the metal sheet is low. Further, when a circuit alteration is made, it is necessary to make a new punching die, which can increase costs.
Further, depending on a circuit configuration, it may be impossible to form the circuit as a single layer. Thus the number of bus bar layers increase.
For example, as shown diagrammatically in FIG. 22A, in connecting circuits C1 and C2 to connectors 7A and 7B of a connector module 2 and to a fuse 8 of a fuse module 3 disposed on the side of the connector module, the circuits C1 and C2 of the connector module 2 cannot be connected to the fuse 8 unless the circuits C1 and C2 are disposed in separate layers. Thereby, the number of layers is increased.
Although the number of component parts mounted on a vehicle has increased rapidly, space for the junction box has remained limited. Thus, it is essential to make the junction box as thin as possible.